The short answer is it depends what the rules say. It sounds like this is cash and will be made out to you directly to be used at a store of their choice or online. It could also be a check for $600 cash.
I would suggest to email the administrator (DL Blair) or the sponsor (P&G) back and ask about the details of the prize. Every time I had a question about a prize, the administrator or sponsor answered it. I am sure they will do the same for you.
Mr. Sweepy
As President of Sweepstakes Today, one of my biggest rewards is reading about your wins and the positive impact it can have on the members.